The 7-2 Chicago Bears have spent the entire 2012 season depending on their defense to land them in the win column. It appears that that trend will continue this Sunday, as starting quarterback Jay Cutler has been ruled out while dealing with a concussion.

In his place, veteran quarterback Jason Campbell will get the start for the Bears as they hope to notch another win against the San Francisco 49ers and maintain their grip on the NFC North.

Cutler exited the Bears’ game this past Sunday night against the Houston Texans shortly after taking a nasty, head-to-head hit from linebacker Tim Dobbins. In response, the NFL slapped Dobbins with an equally-nasty $30,000 fine. Cutler, however, was left with a few loose screws and apparently an indefinite stay on the inactive list.

After showing concussion-like symptoms at halftime, the Bears coaching staff opted to sit Cutler in favor of Campbell. The former first-round pick went on to complete 11 of his 19 passes for 94 yards. He also ran once for five yards as the Bears fell to an equally dominant Texans team.

So far this season, Campbell has only played in four games while serving as backup to Cutler. This, however, will mark his first start since the middle of the 2011 season before he was replaced as the Oakland Raiders’ starting quarterback by Carson Palmer.

The Bears need a big win this week against a tough 49ers team who are also jockeying for playoff positioning. They better hope that the defense is on their game, because the offense took a big hit with Cutler sidelined.

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